3
$\begingroup$

enter image description here

I watched this video on YouTube, which shows an Mi-26 taking off with its rotor tilted forward about 45 degrees. Is the video fake or is it real, and if it is real, how does the Mi-26 do such a thing?

$\endgroup$
4
$\begingroup$

It's real and it's simply the blades running at the flapping hinge limits with the cyclic stick full forward. The blade on the back is at its up limit and the one at the front at its down limit, resulting in an overall disc angle of about 30 degrees off horizontal. It's being done to accelerate along the ground as fast as possible. In the air, the machine's body will follow the tilt of the rotor quickly enough that this sort of angle is almost never experienced unless the pilot made a sudden extreme input in flight.

This (blades hitting flapping limits) is something that only multi-blade articulating rotors can tolerate. You can't do that with a two blade teetering rotor because contacting the blade flapping travel stops, known as mast bumping, will break the mast.

| improve this answer | |
$\endgroup$
  • $\begingroup$ Worth noting that this is being done in order to obtain translational lift as quickly as possible -- suggesting that this is either a heavy or high-performance takeoff. $\endgroup$ – Zeiss Ikon Jan 30 at 13:04
  • 1
    $\begingroup$ @ZeissIkon not necessarily, the RuAF uses running takeoffs routinely because they are safer. $\endgroup$ – AEhere supports Monica Jan 30 at 13:23
  • $\begingroup$ Im gonna pretend I know everything you said.... anyways, you mean the rotors are attached to hinges like on every door? $\endgroup$ – lpydawa Jan 31 at 4:30
  • $\begingroup$ @ipydawa there are many different rotor hub design solutions, the Mi-26 uses a fully articulated one: image $\endgroup$ – AEhere supports Monica Jan 31 at 11:57
  • $\begingroup$ The blades on 3+ blade rotors are traditionally attached to hinges that let them move up and down and when viewed as a whole, looks like a disc tilting this way or that.. On more modern rotors, they do away with the hinges and provide a flexible attachment using either soft bushings (called "elastomeric" bearings or bushings), or just make the blade root flexible like a fishing rod, that allows the blade to do the same thing, but the result is the same. On a two blade system, the blade going up naturally does so in coordination with its opposite partner, allowing a single hinge in the middle. $\endgroup$ – John K Jan 31 at 12:38
0
$\begingroup$

It's less than 45 degrees, I think. Probably less than 30.

There's nothing special about that. That helicopter is built with an important amount of forward cyclic. It's not the rotor head itself that tilts, but the tip-path plane is tilted with the cyclic command...

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.